Quantization Definition and 274 Threads

I will study gravitation quantization(string theory or canonical quantum gravity),so I want to know what are the difficulties of gravitational quantization scheme.I know that quantization means that calculating commutator of quantum field operators via Poisson brackets.Are the difficulties being...

Show that the operators x^2 p_x^2+p_x^2 x^2 and 〖 (xp_x+p_x x)〗^2/2 differ only by terms of order ℏ^2. The attempt at a solution is attached (Postulates.pdf)

I beg my pardon in advance for the stupidity of my question. Is there any "Behind the standard model" paper, document, crazzy theory, essay... exploring a universe where the speed of the light would have several upper limit: c, 2c, 3c, ... N. c? (with c = 3. 108 meter/second) That is.

When (canonically) quantizing a classical system we promote the Poisson brackets to (anti-)commutators. Now I was wondering how much of Poisson bracket structure is preserved. For example for a classical (continuous) system we have $$ \lbrace \phi(z), f(\Pi(y)) \rbrace = \frac{\delta...

This is just a simple question. I am reading about the second quantization but every text I read it starts with something like: suppose we have a set of single particle basis states {la1>,la2>,...,lan>}, which are used to label the wavefunction etc. I just need to make sure I understand what...

Hi, I'm reading www.phys.ethz.ch/~babis/Teaching/QFTI/qft1.pdf and trying to understand the canonical quantization of the Schrodinger field. In particular, the Lagrangian: \begin{equation} \mathcal{L} = \frac{i}{2}\psi^* \partial_0 \psi - \frac{i}{2}\psi \partial_0 \psi^* +...

A short but interesting way of using the CMBR to test the quatization of gravity, what do you think ? Lawrence M. Krauss (1,2), Frank Wilczek (3) ((1) Arizona State University, (2) Australian National Univeresity, (3) MIT) (Submitted on 20 Sep 2013) While many aspects of general...

In classical mechanics you construct an action (involving a Lagrangian in arbitrary generalized coordinates, a Hamiltonian in canonical coordinates [to make your EOM more "convenient & symmetric"]), then extremizing it gives the equations of motion. Alternatively one can find a first order PDE...

1. Hey, So I have to show this proof: \int d^{4}x(-\frac{1}{4}F_{\mu\nu}F^{\mu\nu})=\frac{1}{2}\int d^{4}xA^{\mu}(\square n_{\mu\nu}-\partial_{\mu}\partial_{\nu})A^{\nu} 2. Where F_{\mu\nu}=\partial_{\mu}A_{\nu}-\partial_{\nu}A_{\mu} 3. ok, so I spent forever trying to type...

"Old quantum theory" was derived using "quantization of action" in phase space ##\oint p\,dp = nh## Does "quantization of action" still make sense using canonical quantization?

What is quantisation axis? In many books authors just say that we choose that z is quantization axis.

Why this quantization of energy term occur in quantum mech? Why this "quantization of energy" term occur in quantum mech? Is there any real physical example of quantization of energy? or its just a thought? As i know that if a particle is bound in between two potential walls then the energy of...

In most of textbooks, the canonical quantization procedure is used to quantize the hamiltonian with a simple form, the quadratic form. I just wonder how should we deal with more complex form hamiltonian, such like the ones including interaction terms?

Given that a photon of known wavelength is emitted when an electron goes to a lower energy state, if there are only so many different types of atoms, and only so many electron orbits around those nuclei, the number of wavelengths possible is finite: If true, then the EM spectrum is quantised...

Please, can somebody show me why a Hamiltonian like \sum_nh(x_n) can be written as \sum_{i,j}t_{i,j}a^+_ia_j, with t_{i,j}=\int f^*_i(x)h(x)f_j(x)dx? Thank you.

In order to understand about De-Broglie's explanation on Bohr's second postulate,concept of standing waves should be understood. But condition of λ for a given value of length(string) L is given by L=nλ/s where n =1,2,3 etc. But for a string whose ends are connected together and its shape is...

Homework Statement The general quantization of motion in circular orbits is obtained by combining the equation of motion ## \frac{mv^2}{r} = |\frac{dU(r)}{dr}| ## with the angular momentum quantization condition ## mvr=n\hbar ## Use this procedure to calculate the spectrum for circular...

Essentially how I understand it is, (this is for the quantization of an EM field in vaccum) -Fields become operators, a specific E operator will contain the number and multiple of rising and lowering operators needed to raise a vacuum state into the desired quantum state -The electromagnetic...

State space of QFT,CCR and quantization,spectrum of a field operator? In the canonical quantization of fields, CCR is postulated as (for scalar boson field ): [ϕ(x),π(y)]=iδ(x−y) ------ (1) in analogy with the ordinary QM commutation relation...

I am trying to solve the following problem on an old Quantum Mechanics exam as an exercise. Homework Statement Homework Equations I know that the trace of an operator is the integral of its kernel. \begin{equation} Tr[K(x,y)] = \int K(x,x) dx \end{equation} The Attempt at a...

This is just an idea I had, but I can't seem to find any obvious flaws with it. It's pretty clear that the only description we have of fermions is as quantum objects. There is just no classical analog! Bosons however, have a very natural classical analog. If you just treat the quantum fields...

I have a basic problem about Planck's quantization of energy, ε=hv. It's said that we can only get the integer product of hv, that's the quantilization. But when we plug in v, we can plug any continuous value? Does that mean a particular standing wave in a capacity is specifield a particular v...

Hi, This is my first post and first of all I would like to thank all the contributors to this forum for the amazing amount of information provided here. I’m not a physicist, but I like physics (although I have only a qualitative understanding of it) and I like to smash my brain on difficult and...

So, I'm studying Second Quantization for fermions and came across this equation. I was just wondering why there is a summation needed? And why do we do it with (i≠p).? Please can someone explain this to me? Reply and help is much appreciated.

Hi I have a question on how to work with quantization axis. The setup I am looking at is a single two-level atom placed at the origin (0, 0, 0), which is not perturbed by any magnetic field. I now send in a laser resonant with the transition of the atom. With a right-handed coordinate...

Consider a mode of vacuum zero-point energy at a point in space. Its energy E is related to its frequency f by E = \frac{1}{2}h f. In terms of the mode oscillation period \Delta t the energy is given by E = \frac{1}{2}\frac{h}{\Delta t}. Now let's us imagine that \Delta t becomes smaller and...

Please let me know if I get this right. Second Quantization for Fermions used the definition of its annihilation and creation operators instead of wavefunctions. We use second quantization to express this many body problem in a hamiltonian. Am I right? Can someone please explain this to me in...

there is in general no exact recipe for quantization what does this mean? i think there is only one (correct) quantum mechanics

Imagine a semi-classical birdcage of radius R with N regularly spaced bars individually separated by a spacing a. Now imagine there is a linear light source centered along the cylinder's axis z. Use the dual wave/particle nature of light to show that angular momentum is quantized in the...

I have been reading a lot of stuff on blackbody radiation and the ultraviolet catastrophe. Here is what I have so far. The ultraviolet catastrophe arises from the classical electrodynamics predicting an infinite amount of energy from a blackbody having any temperature. As far as I have...

We know that under charge conjugation the current operator reverses the sign: \hat{C} \hat{\bar{\Psi}} \gamma^{\mu} \hat{\Psi} \hat{C} = - \hat{\bar{\Psi}} \gamma^\mu \hat{\Psi} Here \hat{C} is the unitary charge conjugation operator. I was wondering should we consider gamma matrix...

what is this concept, what are we getting or achieving?? what is the meaning of wavefunction ψ becoming an operator, If that is so, then what are states described by, what do eigen values of psi ψ suggest??

I recently bought "A First Course in Loop Quantum Gravity" by Pullin and Gambini. Partly, I was curious to see what, if anything, had changed in the pedagogy. I also got Bojowald's book a while back. In the final section of "A First Course ..." the authors discuss open problems and broad...

Homework Statement Hi I have a question - it is not homework, but something I have thought about for a long time. I really can't come up with a solution to the problem, and it is driving me crazy. Here is the problem: Say I have a linearly polarized monochromatic wave incident on an...

Hi Please see the attached picture. It shows an atom, the filled black circle, which consists of a J=0 level (with m=0 sublevel) and J'=1 (with m' = +/- 1 sublevels). From the left is a nearly monochromatic laser impinging on the atom, which is linearly polarized along the same direction of...

Hi, I have a situation where I have a set of n data points and want to specify k values that best approximate the values in the set. (it's an image-color reduction problem) MATLAB has a magic algorithm using something called minimum-variance quantization that will do this (although I...

Hello everyone, For a project that may involve some work with Anti de Sitter space, I want to understand 1. what the AdS metric looks like 2. how to set up and solve boundary value problems in AdS, e.g. scalar field KG equation in AdS 3. how to quantize scalar fields in AdS For 1, I...

Hello ! I had my fair share of quantum mechanics already :) But today I was wondering something, kind of odd I thought of this so late ... But do continuous energy levels really excist or is it just an approximation. I am asking this cause by my understanding energy is quantized, so...

relation between "commutation" and "quantization" Hi people; Over the several texts I have read, I got the impression that position-momentum commutation relations is the cause of "quantization" of the system. Or, they are somehow fundamentally related. The only relation I know of, is to...

As I understand (from reading p. 2-06 of Marle's 1975 text on geometric quantization available on the french wiki page on "quantification géométrique") , there are physical situations where we do not know how to write the Schrodinger equation. Namely, we do not know what operator to take as the...

There is an issue with the new paper by Bonzom and Smerlak on cellular quantization of geometry, which surfaces in an obscure footnote #5 on page 5 at the end. The paper http://arxiv.org/abs/1201.4996 appears to resolve most or all of the outstanding doubts concerning the Loop program. That...

Hi all, I was curious about mathematics and physical meaning behind first and second quantization formalisms of schrodinger's equation. what do these mean? Okey, third quantization formalism may be weird/new for many but its associated with wheeler dewitt equation.

Hello everyone, I'm having some trouble, that I was hoping someone here could assist me with. I do hope that I have started the topic in an appropriate subforum - please redirect me otherwise. Specifically, I'm having a hard time understanding the matrix elements of the density matrix...

I'm really getting frustrated right now, as I am unable to reproduce the two-point gauge-field correlation function (i.e. propagator) as derived from the path integral in an R_\xi gauge using operators from canonical quantization. I believe the polarization 4-vectors of the gauge field ought to...

Theoretically, how much energy in particle accelerator would be required to quantize a graviton from a gravity field?

I have an example class yesterday, but one question troubled me. In part (b), why does E=nhf? For me, it seems E=nh is enough, why does the equation involve frequency f after quantization?

Homework Statement I'm taking physical chemistry 2 right now and we are discussing the basics of quantum mechanics, and I'm trying to understand black body radiation and the ultraviolet catastrophe. What I don't understand is how quantization and Plancks distribution fix the ultraviolet...

I apologize in advance if this is too trivial, but... Time and again, I hear something along the lines of "Plank's constant is a unit of action", or "Plank's constant is a unit of action in the old quantum theory". In addition, many texts imply some sort of connection between quantization of...

I've heard that the quantum mechanics of particles in a potential is called 1st quantization which produces wavefunctions. And I've heard that quantum field theory is called 2nd quantization which in turn quantizes the wavefunctions. Can this process be iterated to give 3rd quantization, and...

Homework Statement What are the similarities and differences between the quantization of angular momentum in the Schrodinger theory and in the Bohr model? Homework Equations ? The Attempt at a Solution Similarities: -In both theories, the principal quantum #, n, determines the...